Inside diameter measuring tool

Abstract

An inside diameter measuring tool includes: a main body; an axially moving spindle having a male screw to be screwed to the main body; a plurality of contact pieces provided on the main body, the measuring pieces moving in a direction substantially orthogonal to the axial direction of the spindle; and a conical member interposed between the contact pieces and the spindle, the conical member advancing and retracting the contact pieces in the direction substantially orthogonal to the axial direction of the spindle. The lead of the male screw of the spindle is 1.0 mm or more and the cone angle of the conical member is less than 53 degrees. Preferably, the lead of the male screw is 2.0 mm and the cone angle of the conical member is approximately 28 degrees.

Description

[0001]The entire disclosure of Japanese Patent Application No. 2008-182569, filed Jul. 14, 2008, is expressly incorporated by reference herein.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an inside diameter measuring tool.[0004]2. Description of Related Art[0005]An inside diameter measuring tool called as a Holtest has been known as a device for measuring an inner diameter of an object to be measured. The inside diameter measuring tool includes: a body; an axially moving spindle having a screw to be screwed to the body; a plurality of contact pieces provided on the body, the contact pieces advancing and retracting in a direction substantially orthogonal to the axial direction of the spindle; and a conical member interposed between the contact pieces and the spindle, the conical member moving the contact pieces in the direction substantially orthogonal to the axial direction of the spindle in accordance with the axial movement of th...

AI Technical Summary

Benefits of technology

The present invention provides an inside diameter measurement tool that improves operability, efficiency, and accuracy while minimizing friction between contact pieces and a conical member for enhanced durability. The tool includes a main body, a spindle with a screw, and multiple contact pieces that move in a direction perpendicular to the spindle. A conical member is interposed between the contact pieces and the spindle, which moves the contact pieces in the same direction as the spindle. The lead of the screw is 1.0 mm or more, and the cone angle of the conical member is less than 53 degrees. This design allows for easier measurement of objects, reduces the number of rotations of the spindle, and increases the distance between the contact pieces and the conical surface, reducing friction and improving durability.

Problems solved by technology

However, since the lead of the screw of the spindle of the inside diameter measuring tool is 0.5 mm, when an operator measures objects of various size, he has to undergo a number of rotation of the screw of the spindle in order to advance and retract the contact pieces, resulting in deteriorated operability and operation efficiency.

Consequently, the frictional force caused on the portion on which the contact pieces slide on the conical member increases as compared with the typical arrangement, which is likely to deteriorate the durability of the contact pieces and the conical member.

In other words, the contact pieces is greatly displaced for a relatively small amount of displacement of the spindle, which lowers the measurement accuracy.

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